Have an 03 Cigarett with 500 efi’s, 568 hours on boat but fresh motors. I started losing some rpm and could start hearing brackfire out of the exhaust above 3k or so. Engine would start, idle, and cruise up to around 3k with no issues. Noticed fuel pressure gauge was only at around 18 lbs? Checked all plugs and no fouling or wet plugs, all looked good. Other engine is right at 40 psi. I replaced the cool fuel elec fuel pump and regulator, made no change on fuel gauge whatsoever? Where else can I look? Any advice would be appreciated. Mike

Check for collapsed fuel supply lines, dirty/clogged fuel filter, or clogged fuel tank vent.

look for a restriction.sounds like line from tank to pump could be collapsing and pull anti siphon valve at tank and see if its clogged up at all.

It shouldn’t start/idle/and run up to 3k like normal with only 18psi. I’d use a mechanical gauge to test fuel psi.

Or is fuel psi normal till 3k and then drops to 18psi when over 3k ?

Pop’s out of exhaust could be injector timing issue , ignition timing issue, (cam sensor/ign module/or ??) valve spring issue/, or etc also.

Saw the same issue last year. Fuel filter was clogged. Hope yours as simple. Isn't there a hidden filter on the 500EFI's?

Probably has a bad mechanical pump.

I swapped the fuel filters from my other motor, they spin on above the lift/mechanical pump

I made sure fuel filter was completely full and turned key to run the elec pump and still no change in psi.

maybe my gauge is reading wrong, I can try and change the gauge or use a mechanical gauge on the engine? Test the fuel pressure with mechanical gauge at the fuel dampener or somewhere else?

appreciate all the advice guys

#4 is the schrader valve on your fuel rail for using a fuel psi checker. You can rent for free auto part stores like Autozone.